STC3115 configuration

[roland van straten]

Posted on March 16, 2018 at 11:53

Dear,

Is it possible to adapt the table of SOC values in the STC3115 so I can use a 4.35V (-IQT) version in a situation where I need a 4.2V (AIQT) version of the chip? See AN4324 page 9.

Regards,

Roland

#stc3115 #soc

[Gregory Go.]

Posted on April 12, 2018 at 03:02

Hi,

The default OCV table is hardcoded in STC3115 (compared to STC3117 where the table is fully configurable by user). And the table values are different if you select the *IJT or *AIJT chip version.

The OCV curves in the following document show the min/max values possible for the OCV characteristic of your battery.

https://github.com/st-sw/STC3115GenericDriver/blob/master/Docs/Config/STC3115%20OCV%20curve%20-%20default%20register%20values.pdf

As long the the full OCV curve of the battery is located between the min and the max, you will get a good SOC accuracy from the gas gauge.

At page 3 of the document, you can see that for STC3115IQT the minimum OCV value required to display 100% is 4242.6V

So if you use STC3115IQT (4.35V version) to measure a 4.2Vmax battery, the fuel gauge may never reach the 100%. So you won't have a correct accuracy at the end of charge.

You can add a workaround in the software driver to force manually the REG_SOC to 100% if the measured SOC is >90% and the measured Voltage is 4.2V (or close to it).

Regards